Drug-induced tremor is involuntary shaking due to the use of medication. Involuntary means you shake without trying to do so. The shaking occurs when you move or try to hold your arms, hands, or head in a certain position. It is not associated with other symptoms.
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Guillain-Barré syndrome is a serious health problem that occurs when the body’s defense (immune) system mistakenly attacks part of the nervous system. This leads to nerve inflammation that causes or paralysis and other symptoms.

Stereotypic movement disorder is a condition in which a person makes repetitive, purposeless movements (such as hand waving, body rocking, or head banging). The movements interfere with normal activity or have the potential to cause bodily harm.